The concept of driving a single output gear through a pair of idler pinions from the single input gear is desirable in order to reduce gear tooth loading and to reduce gear sizes and gear box dimensions with a resulting reduction in weight of the unit. Uniform load distribution or a torque split between the idlers is essential to obtain the advantages of this concept. However, with rigid gear mountings, tolerances in manufacturing make it impossible to obtain a consistently equal torque split between the pinion and the two idlers, and therefore it is impossible to take full advantage of the benefits available from the power split.